Rheostat



Patented Oct. 31, 1922.

1 UNITED) srA'rBs HARRY C. NAGEL, OI WILKINBBUEG, PENNSYLVANIA,

AQSIGNOE TO WESTINGHOUSE ELECTRIC & IANU'IACTUBING COMPANY, A COEPOEATIONOI' PENNSYLVANIA.

EHEOBTAT.

Application fled December 22, 1919. Serial nouuam.

To all whom it may concern Be it known that I, HARRY C. NAGEL, a

citizen of the United States, and a resident of Wilkinsbur ,-in the county of Allegheny and State of ennsylvania, have invented a new and useful Improvement in Rheostats, of which the following is a specification. My invention relates to rheostats and it I has for its object to provide a rheostat that is simple and compact in structure and is economical in manufacture.

Resistance devices constructed in accordance with my, invention are particularly adapted for use in connection with smal electric motors, for controlling electric lighting circuits, and for any application where a very gradual change in the value of current is desirable. I provide a pair of ref sistors in side-by-side relation and a ball of steel, or other suitable conducting material, "which rests upon both resistorsand may be rolled by suitable actuating means from one end of the resistors to the other to graduall shunt the resistors.

' T e details of my invention will be described in connection with the accompan ing drawing in which Fig. 1 is a longitu inal sectional view of a rheostat constructed in accordance with my invention; Fig. 2 is a View, in transverse section, of the mechanism of Fig. 1; Fig. 3 is a view, In side elevation, of a resistor; Fi 4 is a sectional view taken on line IV- V of Fig. 3 and Fig. 5 is a diagrammatic view of a portion of an electrical system embodying my invention.

Referring 1particularly to Figs. land 2, a casing 1 0 substantiall polygonal cross section, supports a pair 0 resistors 2 which are ri idly held in position by the end plates 3 of t e casing. The resistors 2, which are of rectangular cross section, are arranged in side-by-side relation with their uppersides inclined toward each other. The casing has a broad base and its sides are so bent as to partially cover the resistors.

e resistors are controlled by a movable ball 4 which is actuated by means of a holdin member 5 that is slidably mounted on a rod 6. The member 5 has a cup-shaped recess 7 within which the ball 4 is loosely mounted and within which is a spring 8 for maintaining a ielding enga ement between the ball and t e resistors. lhe member 5 has a knob 9 which projects through 11. kmgitudinally-extendinggroove 10 in the top of the casin As best sfiqwn in Figs. 3 and 4, each of the resistors 2 comprises a metallic core member 11 that is surrounded by layers of insulating material. The insulating material may consist, for exam 1c, of layers of mica and suitable paper in icated at 12 and an outer covering of asbestos 13. A resistance element 14, of bare wire, is wound over the asbestos and retained in position by a layer of cement 15, or'other suitable means,

which entirely covers the resistance element except that portion of the surface which is brought in contact with the ball 4. The re sistance elements 14 of resistors 2 are electrically connected at one of their adjacentends .by a suitable conductor and, at the other ends, each element 14 is connected to a circuit to becontrolled b a lead 16. (See F i :5 of the drawing.)

o o erate the rheostat, the operator may grad-11a ly introduce resistance by slidingthe holder 5 from its position, as shown in Fig. 1 of the accompanying drawing, along the rod 6, thus causing the steel contact ball to roll over the resistance elements 14 and thereby. gradually insert the resistors in the circuit' When. the holder 5 reaches the other end of the casing, the current-traverses the entire length of the resistors. The operator may decrease the resistance in the circuit by reversing the direction of the movement of the holder 5 until it is returned to the position in which it is'shown in the drawing, in which position, the steel contact ball 14 shunts all the resistance and completesa direct connection between'the two leads 15.

The side-by-side arrangement of the resistors and their series relation permit the ball to shunt double the value of'resistance that would be possible if only one resistor were employed. The side-by-side relation of the resistors also prevents lateral movement of the spherical member.

The use of a resiliently mounted spherical contact member insures a good contact with the resistance elements as the sphere not onlyv rests upon the windings but projects slightly between them. The rollin motion of the sphere permits it to be easi y moved over the surface of the resistors.

Although I have described a simple and preferred form of my invention, I desire that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. In a' resistance device, the combination with two resistors in sideby-side relation, of a contact member for gradually shunting turns of the said resistors, and means for effecting a rolling movement of said contact member.

2. In a resistance device, the combination with two resistors in side-by-side relation, of a single spherical contact member for gradually shunting turns of said resistors, resilient means for maintaining said contact member in contact relation with said resistors, and means for efi'ecting movement of said contact member throughout the length of said resistors.

3. In a resistance device, the combination with two resistors in side-by-side relation, of a loosely-mounted spherical contact member for shunting turns of said resistors, and means for effecting rollin contact relation of said contact member with the said resistors throughout their length.

4. In a resistance device, the combination with two resistors in side-by-side relation, of a spherical contact member for gradually shunting turns of said resistors, a cupshaped holder for positioning said contact member, a resilient means for maintaining said contact member in contact relation with said resistors, and a guide member upon which said holder is slidably mounted to permit the movement of said holder to bring said contact member in contact with said resistors throughout their length.

5. In a resistance device, the combination with two resistors in side-by-side relation and having sides angularly disposed toward each other, of a contact member for gradually shunting turns of said resistors, and means for effecting movement of said contact member throughout the length of said resistors.

6. In a resistance device, the combination with two resistors in side-by-side relations and having sides angularly disposed toward each other, of a contact member for gradually shunting turns of said resistors, resilient means for maintaining said contact member in contact with said resistors, and means for effecting movement 01 said contact member throughout the length of said resistors.

7. In a resistance device, the combination with two resistors in side-by-side relations and having sides angularly disposed toward each other, of a contact member for gradually shunting turns of said resistors, resilient means for maintaining said contact 'member in contact with said resistors, and means for effecting a slidin movement of said contact member throng out the length of said resistors.

8. In a resistance device, the combination with two resistors in side-by-side relations and having sides angularly disposed toward each other, of a contact member for gradually shunting turns of said resistors, a holder for positioning said contact member, a resilient member for maintaining said contact member in contact relation with said resistors, and a 'uide member upon which said holder is slidably mounted and which permits the movement ofsaid holder and .loosely' mounted for gradually shunting turns of said resistors, resilient means for maintaining said contact member in contact relation with said resistors, and means for effecting rolling movement of said spherical member throughout the length of said resistors.

11. In a rheostat device, the combination with a casing, of two metallic core members in side-by-side relation in said casing and having sides angularly disposed toward each other, insulating means consisting of mica and paper with a binder surrounding the said members, a layer of asbestos superimposed upon the said insulatin means, metallic resistance elements helical y wound upon the said asbestos, a cement covering for protecting and for positioning the said elements, a spherical contact member for gradually shunting turns of the said resistors, a recessed holder for controlling the said contact member,.a resilient member for maintaining the said contact member in contact with the said resistors, and a guide member upon which the said holder is slidably mounted for movement of the holder to actuate said contact member throughout the length of said resistors.

In testimony whereof, I have hereunto subscribed my name this 21st day of November, 1919.

HARRY c. NAGEL. 

